Depending on the purpose and the construction type of the boat, you will find that there are multiple types of boats that you can sail, some more appropriate than others when it comes to use by beginners.
There are a few major categories that most boats will belong to, meaning that they’re either dinghies (small boats that can give you the excitement of sailing with smaller expenses and can prove to be great beginner boats), keelboats (or yachts, sailing boats that you can take out on the ocean and depending on the size even travel around the world with them) and catamarans (boats of all sizes that have two hulls). More categories exist out there, but these would be the main ones.
Since you’re probably not looking to learn about medieval sailing vessels or fishing boats, we’re going to focus below mostly on recreational sailing boats, that can vary quite a bit based on their dimensions, sails and hulls.
Dinghy: a smaller boat that can be used to go out on the ocean, while staying close to the coast. A sailing boat of this type can be used for recreational purposes or for racing. In many cases a rig with a single sail will be used, as it’s easier to maneuver.
Keelboats: these are modern boats of relatively long sizes. The term describes pretty much any sailboat that has a keel and is not large enough to be considered a yacht. They can be used both for racing and for recreation.
Yachts: they’re basically large keelboats that can be used over longer distances. They have enough space to accommodate its occupants overnight in accommodations and they’re considered cruising vessels that can travel across oceans. There are multiple categories within this large one as well, so you’re going to find racing yachts, luxury yachts, cruising yachts, weekender yachts and day sailing yachts.
Pocket Cruisers: also known as pocket yachts, this names describes a sailboat that is small and can be carried on a trailer, yet it has a small cabin onboard. The typical length of such a boat is usually from 10 to 26 ft and its weight is small enough to allow it to be towed on a trailer by regular cars.
Sportsboats: these are sailing boats specifically designed with racing in mind. They will have significantly larger areas for the sails, they use light materials, have modern designs and often enough their crews are used as a counterbalance force.
Catamarans: quite popular lately, catamarans are vessels that have two hulls instead of one. The hulls are parallel to each other and they are connected with some sort of bridge or beam. They have quite a few advantages over regular boats (speed, stability, shallow draught), but there are a few disadvantages as well (maneuverability).
Trimarans: they’re also multihull boats, just like the catamaran, with the difference being that the trimaran has three hulls instead of two. The one in the middle is big, with two smaller ones on the sides giving it more stability. Built for racing and for recreation purposes, trimarans have both pros and cons.